Not counting trap links. Stuff not meant for trolling.
EDIT: And how old are you now?
I first saw adult material in Firefly. It didn't show anything under the sheets but it was clear what was going on. I then poured water on my dad's head and walked off. They didn't warn me and I didn't want to see that.
Another question, when do you think it's acceptable to first see this? What age or other criteria?